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 A018933 From the game of Mousetrap. 1

%I

%S 2,11,50,348,2712,23520,225360,2368800,27135360,336752640,4503340800,

%T 64585382400,989138304000,16115529830400,278360283801600,

%U 5081622594048000,97772197146624000,1977622100213760000

%N From the game of Mousetrap.

%D Mundfrom, Daniel J.; A problem in permutations: the game of `Mousetrap'. European J. Combin. 15 (1994), no. 6, 555-560.

%p c := proc(n,x) local a,i; if n > x+1 then a := (n-2)! ; for i from 3 to x do a := a+(-1)^i*(binomial(x-2,i-2)+binomial(x-3,i-3))*(n-i)! ; od: fi; a ; end: A018933 := proc(n) if n = 5 then 2 ; elif n = 6 then 11 ; else c(n,5) ; fi: end: for n from 5 to 23 do printf("%d,",A018933(n)) ; od: [From _R. J. Mathar_, Oct 02 2008]

%Y Cf. A002468.

%K nonn

%O 0,1

%A _N. J. A. Sloane_.

%E This entry was corrupted by a misplaced edit Nov 30 2007; previous (and correct) version restored by _N. J. A. Sloane_ Jan 25 2008

%E More terms from _R. J. Mathar_, Oct 02 2008

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